| 1. |
- Etana, Ararso, et al.
(author)
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Readily dispersible clay and particle transport in five Swedish soils under long-term shallow tillage and mouldboard ploughing
- 2009
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In: Soil and Tillage Research. - : Elsevier BV. - 0167-1987 .- 1879-3444. ; 106, s. 79-84
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Journal article (peer-reviewed)abstract
- Soil disturbance by tillage and traffic often adversely affects aggregate stability, leading to colloid and particle mobilisation, which may result in crusting, low water infiltration rate and sediment transport. Hence, minimising soil tillage is an important step in conserving soil quality. This study investigated readily dispersible clay (RDC) and particle transport as affected by shallow tillage or mouldboard ploughing in five Swedish long-term reduced tillage experiments that had been underway for 15-31 years at the time of soil sampling. The soils of the experimental sites are Eutric and Dystric Cambisols. RDC of soil samples, collected in 0-10 cm and 12-17 cm depth, from mouldboard ploughed (MP) and shallow tillage (ST) plots was compared by measuring turbidity. Particle transport was also determined in undisturbed soil columns (20 cm in diameter and 20 cm high) from these treatments. RDC and particle transport were significantly lower for ST than for MP at three sites where clay content was above 30%. Particle transport in two soils (clay content above 40%) increased with irrigation events, indicating that preferential transport dominated in unsaturated soil columns, but matrix flow and, consequently, particle dispersion increased as the soil approached saturation. Despite more organic C accumulation in the upper 0-10 cm of ST than in the 12-17 cm soil layer, clay dispersion was lower in the latter. Particulate P (Total P - dissolved P) was well-correlated to turbidity, suggesting that analysis costs often can be cut by only measuring turbidity. Shallow tillage generally produced positive environmental effects without negative effects on crop yield, especially on soils with high clay content. (C) 2009 Elsevier B.V. All rights reserved.
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| 2. |
- Farage, P. K., et al.
(author)
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The potential for soil carbon sequestration in three tropical dryland farming systems of Africa and Latin America: A modelling approach
- 2007
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In: Soil & Tillage Research. - : Elsevier BV. - 0167-1987. ; 94:2, s. 457-472
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Journal article (peer-reviewed)abstract
- Historically, agriculturally induced CO2 release from soils has contributed to rising levels in the atmosphere. However, by using appropriate management, soils can be turned into carbon sinks. Many of the dryland regions of the world are characterised by degraded soils, a high incidence of poverty and a low capacity to invest in agriculture. Two well-proven soil organic matter models (CENTURY 4.0 and RothC-26 3) were used two explore the effects of modifying agricultural practices to increase soil carbon stocks. The changes to land management were chosen to avoid any significant increase in energy input whilst using technologies that would be available without radically altering the current agricultural methodology. Case studies were selected from dryland farming systems in Nigeria, Sudan and Argentina. Modelling showed that it would be possible to make alterations within the structure of the current farming systems to convert these soils from carbon sources to net sinks. Annual rates of carbon sequestration in the range 0.08-0.17 Mg ha(-1) year(-1) averaged over the next 50 years could be obtained. The most effective practices were those that maximised the input of organic matter, particularly farmyard manure (up to 0.09 Mg ha(-1) year(-1)), maintaining trees (up to 0.15 Mg ha(-1) year(-1)) and adopting zero tillage (up to 0.04 Mg ha(-1) year(-1)). Verification of these predictions will require experimental data collected from field studies. (C) 2006 Elsevier B.V. All rights reserved.
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| 3. |
- Håkansson, Inge
(author)
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Long-term effects of no-tillage on dynamic soil physical properties in a Rhodic Ferrasol in Parana, Brazil
- 2009
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In: Soil and Tillage Research. - : Elsevier BV. - 0167-1987 .- 1879-3444. ; 103, s. 158-164
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Journal article (peer-reviewed)abstract
- No-tillage has been adopted worldwide as a strategy to reduce the negative effects of soil erosion in conventional tillage. However, no-tillage can lead to over-compaction of the soil, which can have detrimental effects on soil structure and on crop yield. The objective of this study was to evaluate the soil physical functionality of a Rhodic Ferrasol under long-term no-tillage. The following physical properties were measured: dry bulk density (Db), total porosity (Pt) and macroporosity as well as saturated hydraulic conductivity (K(sat)) and intrinsic air permeability (K(a)). Physical quality of the soil was also evaluated by the S index at each depth increment. The study was carried out in a Rhodic Ferrasol under a 14-year old, no-tillage system in Ponta Grossa, Parana, Brazil. Undisturbed soil samples were collected at depths of 0-0.10, 0.20-0.30, 0.40-0.50, and 0.60-0.70 m. The soil properties such as dry bulk density, total porosity and macroporosity showed the presence of a denser layer at a depth of 0.20-0.30 in. The Db and Pt values in this layer were significantly different from the other layers. However, the values of 1.23 Mg m(-3) for Db, 0.52 m(3) m(-3) for Pt, and 0.17 m(3) m(-3) for macroporosity were all still adequate for the growth and development of roots at this layer. The values of K(sat) and K(a) were higher at the surface layer than deeper layers. The lowest values were around 80 and 70% in comparison with surface, respectively to the depths of 0.40-0.50. and 0.60-0.70 in K(sat) and K(a) values were 7.79 x 10(-5), 2.76 x 10(-5), 1.58 x 10(-5), and 1.91 x 10(-5) m s(-1), and K(a) values were 3.70 x 10(-11), 2.04 x 10(-11), 7.69 x 10(-12), and 1.10 x 10(-11) m(2) for the depths of 0-0.10, 0.20-0.30, 0.40-0.50, and 0.60-0.70 m, respectively. This demonstrated that better conditions for the exchange of gases and water existed in the layers above 0.30 m. The S index indicated that the soil had good structure in all layers studied, with values above 0.035, but that a small increase in Db in the 0.20-0.30 m layer could lead to deterioration of the soil structural quality. The long-term use of no-tillage resulted in increases of organic carbon and pore connectivity in the surface layer, providing functionality in the soil. (C) 2008 Elsevier B.V. All rights reserved.
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| 4. |
- Larsbo, Mats, et al.
(author)
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Herbicide sorption, degradation, and leaching in three Swedish soils under long-term conventional and reduced tillage
- 2009
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In: Soil and Tillage Research. - : Elsevier BV. - 0167-1987 .- 1879-3444. ; 105, s. 200-208
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Journal article (peer-reviewed)abstract
- Soil tillage has the potential to influence water flow and solute transport through the soil by cutting continuous macropores which connect the soil surface to the subsoil. Tillage also affects soil organic carbon sequestration which may lead to different sorption and degradation properties depending on the long-term tillage practices. The objective of this study was to quantify the differences in sorption, degradation and leaching of the herbicides bentazone and isoproturon between conventional tillage (CT) and reduced tillage (RT) under Swedish conditions. Three sites, Ultuna (silty clay), Saby (loam), and Lonnstorp (sandy loam moraine till), where replicate plots had been under either CT or RT for at least 9 years, were included in the study. A higher organic carbon content had developed in the top 5 cm of RT plots compared to the 10-20 cm depth and CT plots since the establishment of the experimental treatments. Adsorption and degradation were studied in laboratory experiments and solute transport was studied in undisturbed column experiments using non-reactive tracers and herbicides. The results from the column experiments were not significantly different between tillage treatments for Saby and Lonnstorp. For Ultuna, RT resulted in a more pronounced preferential tracer transport pattern and isoproturon leaching was twelve times larger compared to CT columns. This indicates that the tillage treatment had affected the macropore connectivity only at Ultuna. Freundlich adsorption coefficients for both bentazone and isoproturon were larger (though not always significantly) in the top 5 cm of RT soil compared to the 10-20 cm depth and to CT, reflecting the higher organic carbon content. The degradation rate was also generally larger (though not always significantly) in the top 5 cm of RT soil. These results show that RT has the potential to reduce pesticide leaching. However, any such reduction may be counter-balanced by enhanced preferential flow for soils where RT results in improved macropore connectivity. (C) 2009 Elsevier B.V. All rights reserved.
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| 5. |
- Lövdahl, Lars, et al.
(author)
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Effects of mulching and catch cropping on soil temperature, soil moisture and wheat yield on the Loess Plateau of China
- 2009
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In: Soil and Tillage Research. - : Elsevier BV. - 0167-1987 .- 1879-3444. ; 102, s. 78-86
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Journal article (peer-reviewed)abstract
- Soil management can notably influence crop production under dryland farming in semiarid areas. Field experiments were conducted, from October 2001 to September 2004, with an attempt to evaluate the effects of field management regimes on thermal status at an upland site; and soil water and wheat production in a winter wheat (Triticum aestivum L) system at upland, terrace land and bottom land sites on the Loess Plateau, China. The field management regimes tested were: (i) the conventional practice (winter wheat followed by a ploughed summer bare fallow); (ii) conventional management, but a catch crop growing for certain time during fallow period used as green manure (after the wheat harvest, a catch crop were directly sown. instead of ploughing, and then incorporated into the soil roughly one month before wheat sowing); and (iii) wheat straw mulch (0.8 kg m(-2)), covering the soil throughout the year during the experimental period (no summer ploughing, straw was removed during wheat sowing). Soil temperature under catch cropping was lower during certain period of its growing by about 2 degrees C, slightly higher for short spells after incorporation and before wheat harvest, no observed effects during the rest time of a year relative to conventional practice at the upland site. Moreover, soil water storage levels under catch cropping were comparable with those of the conventional practice for all three years, but wheat yield substantially declined in the last year. Mulching showed different responses for the three land sites. At the upland site, daily mean soil temperatures under mulching at 10 cm depth were decreased in the warmer period by 0-4 degrees C, and increased in the colder period by 0-2 degrees C when compared to those of non-mulched soil. At upland and bottom land sites, mulching conserved an average of 28 and 20 mm more water in the upper 100 cm soil layer at the time of wheat sowing, respectively, than conventional practice. However, at the terrace, mulching had little effect on soil water storage, nor on wheat grain yield, relative to conventional practice. Therefore, considering the limited availability of mulch material in this region and the economic benefits, it is recommended that mulching may be beneficial to upland or bottom land, but not to terraced land. In addition, the application of catch cropping in this study did not show positive effects, the more comprehensive evaluation of this approach would be further needed. (C) 2008 Elsevier B.V. All rights reserved.
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| 6. |
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| 7. |
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| 8. |
- Zhang, Shulan, et al.
(author)
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Modelling the effects of mulching and fallow cropping on water balance in the Chinese Loess Plateau
- 2007
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In: Soil & Tillage Research. - : Elsevier BV. - 0167-1987 .- 1879-3444. ; 93:2, s. 283-298
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Journal article (peer-reviewed)abstract
- To improve water use efficiency on drylands it is essential to understand the mechanisms affecting water balance partitioning in arable land ecosystems. A field experiment was conducted, from October 2001 to October 2004, to evaluate the effects of field management regimes on water balance and water use efficiency in a winter wheat (Triticum aestivum L.) system in the Loess Plateau, China. The field management regimes tested were: (i) conventional agricultural management (winter wheat followed by a ploughed summer fallow); (ii) conventional management plus a fallow crop used as green manure; (iii) application of wheat straw mulch (0.8 kg m(-2)), which was retained throughout the year (no summer ploughing). A process-oriented ecosystem model (CoupModel) was calibrated with field measurements of soil water contents, leaf area indices, plant heights and crop yields, then used to generate comparative simulations of the water balance partitioning under the wheat straw mulch, fallow crop and conventional management regimes. The simulations indicated that during the experimental period mulching increased soil water storage by 5-8%, decreased soil evaporation by 11-13%, and increased wheat transpiration by 2-5% compared with the conventional management regime, thus increasing the wheat yield and water use efficiency. Furthermore, water reached deeper horizons under mulching than under conventional practice, resulting in 15% more deep percolation in a wet year. The simulation results also indicated that growing green manure during the fallow period decreased soil water storage, leading to lower wheat yields. Mulching proved to be an efficient measure for increasing yields, and possibly contributed to groundwater recharge.
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| 9. |
- Bredie, W.L.P., et al.
(author)
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Methods for artificial perception : Can machine replace man?
- 2006
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In: Developments in Food Science. - 0167-4501. ; 43:C, s. 617-618
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Journal article (peer-reviewed)abstract
- The previous 'Scandinavian' Weurman Flavour Symposium held in Oslo, Norway, in 1987 had as the main themes chemistry, biotechnology, sensory science and data analysis in flavour research [1]. Since then, many advances have been made, however, when comparing with the Weurman Symposium in 2005, the subject areas and topics of research have not changed very much. Flavour scientists still work with identification of aroma and taste components in foods, their formation, stability and release as well as sensory and data analytical aspects. The knowledge about flavour components in foods and the understanding of the way we perceive them has though considerably expanded. Advances have also been made in the way one can analyse flavours in foods and beverages, and measure responses from and in human subjects. One can say that the toolbox with methods and techniques for flavour analysis has expanded remarkably offering many new possibilities to understand flavour from different perspectives and levels of details. The workshop presented some state-of-the-art applications of modern in vivo and in vitro flavour analysis as well as visual sensory assessments of meals made by machines equipped with sensors and artificial networks processing capability. Also, new ways of studying multisensory processes by stimulating sensory subjects with defined stimuli were discussed. Intelligent 'artificial perception' systems may replace some routine sensory analysis and monotonous production tasks in the future, but the development of such systems still require sensory assessments by humans. © 2006 Elsevier B.V. All rights reserved.
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